The field of the invention relates generally to uninterruptible power supplies, and more particularly, to multi-mode medium-voltage uninterruptible power supplies.
Uninterruptible power supplies (UPS) are used in many applications such as in data centers and hospitals to provide quality power to a load without interruption, including during outages or disturbances in the AC mains supply voltage. Typically, UPSs are rated to receive AC voltage from a low voltage (e.g. 380V-480V) distribution network and supply a three-phase voltage to the load. As the size of data centers increases, powering up critical loads through a low voltage UPS is a challenge as the current magnitude increases significantly, even reaching the limits of the low voltage switchgear. Processing the power at a higher voltage (e.g. 4.16 kV or 13.8 kV) causes the current to be handled by the UPS and the output cables to decrease. The voltage is then stepped down at the point of load. Accordingly, medium voltage conversion in the UPS (e.g. 4.16 kV or 13.8 kV) has advantages with respect to increased operating efficiency and reduced cabling cost.